CHICAGO - No. 3 U.S. railroad CSX Corp said on Tuesday its third-quarter net profit fell slightly, mainly on slumping coal freight volumes, and that “significant coal headwinds” will continue into 2016. However, earnings beat analysts’ expectations as cost cuts, steps to improve efficiency, and lower fuel costs offset a 3 percent decline in overall freight volumes. CSX shares rose more than 1.7 percent, or 46 cents, to $28.71 in extended trading. Like most other railroads, CSX has suffered from a sharp decline in coal freight volumes this year as utilities switch to burning cheaper natural gas, and the strong U.S. dollar hurt exports. In the third quarter, every category of freight CSX hauls declined, but coal alone accounted for almost half of a 9 percent drop in revenue from the year-ago quarter. Coal revenue fell 19 percent to $583 million from $721 million a year earlier. The Jacksonville, Florida-based company reported net income of $507 million, or 52 cents per share, down from $509 million, or 51 cents per share, in the year-ago quarter. Analysts had on average expected earnings per share of 50 cents. The results demonstrated CSX’s “ability to leverage improving service while controlling costs in a dynamic environment where commodity prices and the strength of the U.S. dollar are challenging many of our markets,” Chief Executive Michael Ward said in a statement. CSX’s revenue fell to $2.94 billion from $3.2 billion in the year-ago quarter. Analysts had expected $2.97 billion. The company said coal revenue should decline about $450 million in 2015. That would represent a nearly 16 percent drop from $2.85 billion in 2014.